History of PHP

PHP Tools, FI, Construction Kit, and PHP/FI

PHP as it's known today is actually the successor to a
product named PHP/FI. Created in 1994 by Rasmus Lerdorf,
the very first incarnation of PHP was a simple set of
Common Gateway Interface (CGI) binaries written in the C
programming language. Originally used for tracking visits
to his online resume, he named the suite of scripts "Personal
Home Page Tools," more frequently referenced as "PHP Tools."
Over time, more functionality was desired, and Rasmus rewrote
PHP Tools, producing a much larger and richer implementation.
This new model was capable of database interaction and more,
providing a framework upon which users could develop simple dynamic
web applications such as guestbooks. In June of 1995, Rasmus
» released
the source code for PHP Tools to the public, which allowed
developers to use it as they saw fit. This also permitted -
and encouraged - users to provide fixes for bugs in the code,
and to generally improve upon it.

In September of that year, Rasmus expanded upon PHP and - for a
short time - actually dropped the PHP name. Now referring to the
tools as FI (short for "Forms Interpreter"), the new implementation
included some of the basic functionality of PHP as we know
it today. It had Perl-like variables, automatic interpretation
of form variables, and HTML embedded syntax. The syntax itself
was similar to that of Perl, albeit much more limited, simple,
and somewhat inconsistent. In fact, to embed the code into an
HTML file, developers had to use HTML comments. Though this
method was not entirely well-received, FI continued to enjoy growth
and acceptance as a CGI tool --- but still not quite as a language.
However, this began to change the following month; in October, 1995,
Rasmus released a complete rewrite of the code. Bringing back the
PHP name, it was now (briefly) named "Personal Home Page Construction
Kit," and was the first release to boast what was, at the time,
considered an advanced scripting interface. The language was
deliberately designed to resemble C in structure, making it an easy
adoption for developers familiar with C, Perl, and similar languages.
Having been thus far limited to UNIX and POSIX-compliant systems,
the potential for a Windows NT implementation was being explored.

The code got another complete makeover, and in April of 1996,
combining the names of past releases, Rasmus introduced PHP/FI.
This second-generation implementation began to truly evolve PHP
from a suite of tools into a programming language in its own
right. It included built-in support for DBM, mSQL, and Postgres95
databases, cookies, user-defined function support, and much more.
That June, PHP/FI was given a version 2.0 status. An interesting
fact about this, however, is that there was only one single full
version of PHP 2.0. When it finally graduated from beta status
in November, 1997, the underlying parsing engine was already
being entirely rewritten.

Though it lived a short development life, it continued to enjoy
a growing popularity in still-young world of web development. In
1997 and 1998, PHP/FI had a cult of several thousand users around
the world. A Netcraft survey as of May, 1998, indicated that
nearly 60,000 domains reported having headers containing
"PHP", indicating that the host server did indeed have it installed.
This number equated to approximately 1% of all domains on the
Internet at the time. Despite these impressive figures, the maturation
of PHP/FI was doomed to limitations; while there were several minor
contributors, it was still primarily developed by an individual.

PHP 3

PHP 3.0 was the first version that closely resembles PHP as
it exists today. Finding PHP/FI 2.0 still inefficient and
lacking features they needed to power an eCommerce application
they were developing for a university project, Andi Gutmans and
Zeev Suraski of Tel Aviv, Israel, began yet another complete
rewrite of the underlying parser in 1997. Approaching Rasmus
online, they discussed various aspects of the current
implementation and their redevelopment of PHP. In an effort to
improve the engine and start building upon PHP/FI's existing
user base, Andi, Rasmus, and Zeev decided to collaborate in
the development of a new, independent programming language.
This entirely new language was released under a new name, that
removed the implication of limited personal use that the
PHP/FI 2.0 name held. It was renamed simply 'PHP', with the
meaning becoming a recursive acronym - PHP: Hypertext Preprocessor.

One of the biggest strengths of PHP 3.0 was its strong
extensibility features. In addition to providing end users
with a mature interface for multiple databases, protocols,
and APIs, the ease of extending the language itself attracted
dozens of developers who submitted a variety of modules. Arguably,
this was the key to PHP 3.0's tremendous success. Other key
features introduced in PHP 3.0 included object-oriented programming
support and a far more powerful and consistent language syntax.

In June, 1998, with many new developers from around the world
joining the effort, PHP 3.0 was announced by the new PHP Development
Team as the official successor to PHP/FI 2.0. Active development
of PHP/FI 2.0, which had all-but ceased as of November of the
previous year, was now officially ended. After roughly nine months
of open public testing, when the announcement of the official
release of PHP 3.0 came, it was already installed on over 70,000
domains around the world, and was no longer limited to
POSIX-compliant operating systems. A relatively small share of
the domains reporting PHP as installed were hosted on servers
running Windows 95, 98, and NT, and Macintosh. At its peak, PHP 3.0
was installed on approximately 10% of the web servers on the
Internet.

PHP 4

By the winter of 1998, shortly after PHP 3.0 was officially
released, Andi Gutmans and Zeev Suraski had begun working
on a rewrite of PHP's core. The design goals were to improve
performance of complex applications, and improve the
modularity of PHP's code base. Such applications were made
possible by PHP 3.0's new features and support for a wide
variety of third party databases and APIs, but PHP 3.0 was
not designed to handle such complex applications efficiently.

The new engine, dubbed 'Zend Engine' (comprised of their
first names, Zeev and Andi), met these design goals
successfully, and was first introduced in mid 1999. PHP 4.0,
based on this engine, and coupled with a wide range of
additional new features, was officially released in May
2000, almost two years after its predecessor. In addition
to the highly improved performance of this version, PHP 4.0
included other key features such as support for many more
web servers, HTTP sessions, output buffering, more secure
ways of handling user input and several new language constructs.

PHP 5

PHP 5 was released in July 2004 after long development and several
pre-releases. It is mainly driven by its core, the
Zend Engine 2.0 with a
new object model and dozens of other new features.

PHP's development team includes dozens of developers, as well
as dozens others working on PHP-related and supporting projects,
such as PEAR, PECL, and documentation, and an underlying network
infrastructure of well over one-hundred individual web servers
on six of the seven continents of the world. Though only an
estimate based upon statistics from previous years, it is safe
to presume PHP is now installed on tens or even perhaps hundreds
of millions of domains around the world.